drivers/media/usb/au0828/au0828-i2c.c - kernel/quantenna - Git at Google

 /*
  *  Driver for the Auvitek AU0828 USB bridge
  *
  *  Copyright (c) 2008 Steven Toth <stoth@linuxtv.org>
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

 #include "au0828.h"

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/io.h>

 #include "media/tuner.h"
 #include <media/v4l2-common.h>

 static int i2c_scan;
 module_param(i2c_scan, int, 0444);
 MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

 #define I2C_WAIT_DELAY 25
 #define I2C_WAIT_RETRY 1000

 static inline int i2c_slave_did_write_ack(struct i2c_adapter *i2c_adap)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	return au0828_read(dev, AU0828_I2C_STATUS_201) &
 		AU0828_I2C_STATUS_NO_WRITE_ACK ? 0 : 1;
 }

 static inline int i2c_slave_did_read_ack(struct i2c_adapter *i2c_adap)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	return au0828_read(dev, AU0828_I2C_STATUS_201) &
 		AU0828_I2C_STATUS_NO_READ_ACK ? 0 : 1;
 }

 static int i2c_wait_read_ack(struct i2c_adapter *i2c_adap)
 {
 	int count;

 	for (count = 0; count < I2C_WAIT_RETRY; count++) {
 		if (!i2c_slave_did_read_ack(i2c_adap))
 			break;
 		udelay(I2C_WAIT_DELAY);
 	}

 	if (I2C_WAIT_RETRY == count)
 		return 0;

 	return 1;
 }

 static inline int i2c_is_read_busy(struct i2c_adapter *i2c_adap)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	return au0828_read(dev, AU0828_I2C_STATUS_201) &
 		AU0828_I2C_STATUS_READ_DONE ? 0 : 1;
 }

 static int i2c_wait_read_done(struct i2c_adapter *i2c_adap)
 {
 	int count;

 	for (count = 0; count < I2C_WAIT_RETRY; count++) {
 		if (!i2c_is_read_busy(i2c_adap))
 			break;
 		udelay(I2C_WAIT_DELAY);
 	}

 	if (I2C_WAIT_RETRY == count)
 		return 0;

 	return 1;
 }

 static inline int i2c_is_write_done(struct i2c_adapter *i2c_adap)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	return au0828_read(dev, AU0828_I2C_STATUS_201) &
 		AU0828_I2C_STATUS_WRITE_DONE ? 1 : 0;
 }

 static int i2c_wait_write_done(struct i2c_adapter *i2c_adap)
 {
 	int count;

 	for (count = 0; count < I2C_WAIT_RETRY; count++) {
 		if (i2c_is_write_done(i2c_adap))
 			break;
 		udelay(I2C_WAIT_DELAY);
 	}

 	if (I2C_WAIT_RETRY == count)
 		return 0;

 	return 1;
 }

 static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	return au0828_read(dev, AU0828_I2C_STATUS_201) &
 		AU0828_I2C_STATUS_BUSY ? 1 : 0;
 }

 static int i2c_wait_done(struct i2c_adapter *i2c_adap)
 {
 	int count;

 	for (count = 0; count < I2C_WAIT_RETRY; count++) {
 		if (!i2c_is_busy(i2c_adap))
 			break;
 		udelay(I2C_WAIT_DELAY);
 	}

 	if (I2C_WAIT_RETRY == count)
 		return 0;

 	return 1;
 }

 /* FIXME: Implement join handling correctly */
 static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
 	const struct i2c_msg *msg, int joined_rlen)
 {
 	int i, strobe = 0;
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	u8 i2c_speed = dev->board.i2c_clk_divider;

 	dprintk(4, "%s()\n", __func__);

 	au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

 	if (((dev->board.tuner_type == TUNER_XC5000) ||
 	     (dev->board.tuner_type == TUNER_XC5000C)) &&
 	    (dev->board.tuner_addr == msg->addr)) {
 		/*
 		 * Due to I2C clock stretch, we need to use a lower speed
 		 * on xc5000 for commands. However, firmware transfer can
 		 * speed up to 400 KHz.
 		 */
 		if (msg->len == 64)
 			i2c_speed = AU0828_I2C_CLK_250KHZ;
 		else
 			i2c_speed = AU0828_I2C_CLK_20KHZ;
 	}
 	/* Set the I2C clock */
 	au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

 	/* Hardware needs 8 bit addresses */
 	au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

 	dprintk(4, "SEND: %02x\n", msg->addr);

 	/* Deal with i2c_scan */
 	if (msg->len == 0) {
 		/* The analog tuner detection code makes use of the SMBUS_QUICK
 		   message (which involves a zero length i2c write).  To avoid
 		   checking the status register when we didn't strobe out any
 		   actual bytes to the bus, just do a read check.  This is
 		   consistent with how I saw i2c device checking done in the
 		   USB trace of the Windows driver */
 		au0828_write(dev, AU0828_I2C_TRIGGER_200,
 			     AU0828_I2C_TRIGGER_READ);

 		if (!i2c_wait_done(i2c_adap))
 			return -EIO;

 		if (i2c_wait_read_ack(i2c_adap))
 			return -EIO;

 		return 0;
 	}

 	for (i = 0; i < msg->len;) {

 		dprintk(4, " %02x\n", msg->buf[i]);

 		au0828_write(dev, AU0828_I2C_WRITE_FIFO_205, msg->buf[i]);

 		strobe++;
 		i++;

 		if ((strobe >= 4) || (i >= msg->len)) {

 			/* Strobe the byte into the bus */
 			if (i < msg->len)
 				au0828_write(dev, AU0828_I2C_TRIGGER_200,
 					     AU0828_I2C_TRIGGER_WRITE |
 					     AU0828_I2C_TRIGGER_HOLD);
 			else
 				au0828_write(dev, AU0828_I2C_TRIGGER_200,
 					     AU0828_I2C_TRIGGER_WRITE);

 			/* Reset strobe trigger */
 			strobe = 0;

 			if (!i2c_wait_write_done(i2c_adap))
 				return -EIO;

 		}

 	}
 	if (!i2c_wait_done(i2c_adap))
 		return -EIO;

 	dprintk(4, "\n");

 	return msg->len;
 }

 /* FIXME: Implement join handling correctly */
 static int i2c_readbytes(struct i2c_adapter *i2c_adap,
 	const struct i2c_msg *msg, int joined)
 {
 	struct au0828_dev *dev = i2c_adap->algo_data;
 	u8 i2c_speed = dev->board.i2c_clk_divider;
 	int i;

 	dprintk(4, "%s()\n", __func__);

 	au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

 	/*
 	 * Due to xc5000c clock stretch, we cannot use full speed at
 	 * readings from xc5000, as otherwise they'll fail.
 	 */
 	if (((dev->board.tuner_type == TUNER_XC5000) ||
 	     (dev->board.tuner_type == TUNER_XC5000C)) &&
 	    (dev->board.tuner_addr == msg->addr))
 		i2c_speed = AU0828_I2C_CLK_20KHZ;

 	/* Set the I2C clock */
 	au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

 	/* Hardware needs 8 bit addresses */
 	au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

 	dprintk(4, " RECV:\n");

 	/* Deal with i2c_scan */
 	if (msg->len == 0) {
 		au0828_write(dev, AU0828_I2C_TRIGGER_200,
 			     AU0828_I2C_TRIGGER_READ);

 		if (i2c_wait_read_ack(i2c_adap))
 			return -EIO;
 		return 0;
 	}

 	for (i = 0; i < msg->len;) {

 		i++;

 		if (i < msg->len)
 			au0828_write(dev, AU0828_I2C_TRIGGER_200,
 				     AU0828_I2C_TRIGGER_READ |
 				     AU0828_I2C_TRIGGER_HOLD);
 		else
 			au0828_write(dev, AU0828_I2C_TRIGGER_200,
 				     AU0828_I2C_TRIGGER_READ);

 		if (!i2c_wait_read_done(i2c_adap))
 			return -EIO;

 		msg->buf[i-1] = au0828_read(dev, AU0828_I2C_READ_FIFO_209) &
 			0xff;

 		dprintk(4, " %02x\n", msg->buf[i-1]);
 	}
 	if (!i2c_wait_done(i2c_adap))
 		return -EIO;

 	dprintk(4, "\n");

 	return msg->len;
 }

 static int i2c_xfer(struct i2c_adapter *i2c_adap,
 		    struct i2c_msg *msgs, int num)
 {
 	int i, retval = 0;

 	dprintk(4, "%s(num = %d)\n", __func__, num);

 	for (i = 0; i < num; i++) {
 		dprintk(4, "%s(num = %d) addr = 0x%02x  len = 0x%x\n",
 			__func__, num, msgs[i].addr, msgs[i].len);
 		if (msgs[i].flags & I2C_M_RD) {
 			/* read */
 			retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
 		} else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
 			   msgs[i].addr == msgs[i + 1].addr) {
 			/* write then read from same address */
 			retval = i2c_sendbytes(i2c_adap, &msgs[i],
 					       msgs[i + 1].len);
 			if (retval < 0)
 				goto err;
 			i++;
 			retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
 		} else {
 			/* write */
 			retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
 		}
 		if (retval < 0)
 			goto err;
 	}
 	return num;

 err:
 	return retval;
 }

 static u32 au0828_functionality(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C;
 }

 static struct i2c_algorithm au0828_i2c_algo_template = {
 	.master_xfer	= i2c_xfer,
 	.functionality	= au0828_functionality,
 };

 /* ----------------------------------------------------------------------- */

 static struct i2c_adapter au0828_i2c_adap_template = {
 	.name              = KBUILD_MODNAME,
 	.owner             = THIS_MODULE,
 	.algo              = &au0828_i2c_algo_template,
 };

 static struct i2c_client au0828_i2c_client_template = {
 	.name	= "au0828 internal",
 };

 static char *i2c_devs[128] = {
 	[0x8e >> 1] = "au8522",
 	[0xa0 >> 1] = "eeprom",
 	[0xc2 >> 1] = "tuner/xc5000",
 };

 static void do_i2c_scan(char *name, struct i2c_client *c)
 {
 	unsigned char buf;
 	int i, rc;

 	for (i = 0; i < 128; i++) {
 		c->addr = i;
 		rc = i2c_master_recv(c, &buf, 0);
 		if (rc < 0)
 			continue;
 		pr_info("%s: i2c scan: found device @ 0x%x  [%s]\n",
 		       name, i << 1, i2c_devs[i] ? i2c_devs[i] : "???");
 	}
 }

 /* init + register i2c adapter */
 int au0828_i2c_register(struct au0828_dev *dev)
 {
 	dprintk(1, "%s()\n", __func__);

 	dev->i2c_adap = au0828_i2c_adap_template;
 	dev->i2c_algo = au0828_i2c_algo_template;
 	dev->i2c_client = au0828_i2c_client_template;

 	dev->i2c_adap.dev.parent = &dev->usbdev->dev;

 	strlcpy(dev->i2c_adap.name, KBUILD_MODNAME,
 		sizeof(dev->i2c_adap.name));

 	dev->i2c_adap.algo = &dev->i2c_algo;
 	dev->i2c_adap.algo_data = dev;
 #ifdef CONFIG_VIDEO_AU0828_V4L2
 	i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
 #else
 	i2c_set_adapdata(&dev->i2c_adap, dev);
 #endif
 	i2c_add_adapter(&dev->i2c_adap);

 	dev->i2c_client.adapter = &dev->i2c_adap;

 	if (0 == dev->i2c_rc) {
 		pr_info("i2c bus registered\n");
 		if (i2c_scan)
 			do_i2c_scan(KBUILD_MODNAME, &dev->i2c_client);
 	} else
 		pr_info("i2c bus register FAILED\n");

 	return dev->i2c_rc;
 }

 int au0828_i2c_unregister(struct au0828_dev *dev)
 {
 	i2c_del_adapter(&dev->i2c_adap);
 	return 0;
 }
	/*
	* Driver for the Auvitek AU0828 USB bridge
	*
	* Copyright (c) 2008 Steven Toth <stoth@linuxtv.org>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	*
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	#include "au0828.h"

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/init.h>
	#include <linux/delay.h>
	#include <linux/io.h>

	#include "media/tuner.h"
	#include <media/v4l2-common.h>

	static int i2c_scan;
	module_param(i2c_scan, int, 0444);
	MODULE_PARM_DESC(i2c_scan, "scan i2c bus at insmod time");

	#define I2C_WAIT_DELAY 25
	#define I2C_WAIT_RETRY 1000

	static inline int i2c_slave_did_write_ack(struct i2c_adapter *i2c_adap)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	return au0828_read(dev, AU0828_I2C_STATUS_201) &
	AU0828_I2C_STATUS_NO_WRITE_ACK ? 0 : 1;
	}

	static inline int i2c_slave_did_read_ack(struct i2c_adapter *i2c_adap)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	return au0828_read(dev, AU0828_I2C_STATUS_201) &
	AU0828_I2C_STATUS_NO_READ_ACK ? 0 : 1;
	}

	static int i2c_wait_read_ack(struct i2c_adapter *i2c_adap)
	{
	int count;

	for (count = 0; count < I2C_WAIT_RETRY; count++) {
	if (!i2c_slave_did_read_ack(i2c_adap))
	break;
	udelay(I2C_WAIT_DELAY);
	}

	if (I2C_WAIT_RETRY == count)
	return 0;

	return 1;
	}

	static inline int i2c_is_read_busy(struct i2c_adapter *i2c_adap)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	return au0828_read(dev, AU0828_I2C_STATUS_201) &
	AU0828_I2C_STATUS_READ_DONE ? 0 : 1;
	}

	static int i2c_wait_read_done(struct i2c_adapter *i2c_adap)
	{
	int count;

	for (count = 0; count < I2C_WAIT_RETRY; count++) {
	if (!i2c_is_read_busy(i2c_adap))
	break;
	udelay(I2C_WAIT_DELAY);
	}

	if (I2C_WAIT_RETRY == count)
	return 0;

	return 1;
	}

	static inline int i2c_is_write_done(struct i2c_adapter *i2c_adap)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	return au0828_read(dev, AU0828_I2C_STATUS_201) &
	AU0828_I2C_STATUS_WRITE_DONE ? 1 : 0;
	}

	static int i2c_wait_write_done(struct i2c_adapter *i2c_adap)
	{
	int count;

	for (count = 0; count < I2C_WAIT_RETRY; count++) {
	if (i2c_is_write_done(i2c_adap))
	break;
	udelay(I2C_WAIT_DELAY);
	}

	if (I2C_WAIT_RETRY == count)
	return 0;

	return 1;
	}

	static inline int i2c_is_busy(struct i2c_adapter *i2c_adap)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	return au0828_read(dev, AU0828_I2C_STATUS_201) &
	AU0828_I2C_STATUS_BUSY ? 1 : 0;
	}

	static int i2c_wait_done(struct i2c_adapter *i2c_adap)
	{
	int count;

	for (count = 0; count < I2C_WAIT_RETRY; count++) {
	if (!i2c_is_busy(i2c_adap))
	break;
	udelay(I2C_WAIT_DELAY);
	}

	if (I2C_WAIT_RETRY == count)
	return 0;

	return 1;
	}

	/* FIXME: Implement join handling correctly */
	static int i2c_sendbytes(struct i2c_adapter *i2c_adap,
	const struct i2c_msg *msg, int joined_rlen)
	{
	int i, strobe = 0;
	struct au0828_dev *dev = i2c_adap->algo_data;
	u8 i2c_speed = dev->board.i2c_clk_divider;

	dprintk(4, "%s()\n", __func__);

	au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

	if (((dev->board.tuner_type == TUNER_XC5000) \|\|
	(dev->board.tuner_type == TUNER_XC5000C)) &&
	(dev->board.tuner_addr == msg->addr)) {
	/*
	* Due to I2C clock stretch, we need to use a lower speed
	* on xc5000 for commands. However, firmware transfer can
	* speed up to 400 KHz.
	*/
	if (msg->len == 64)
	i2c_speed = AU0828_I2C_CLK_250KHZ;
	else
	i2c_speed = AU0828_I2C_CLK_20KHZ;
	}
	/* Set the I2C clock */
	au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

	/* Hardware needs 8 bit addresses */
	au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

	dprintk(4, "SEND: %02x\n", msg->addr);

	/* Deal with i2c_scan */
	if (msg->len == 0) {
	/* The analog tuner detection code makes use of the SMBUS_QUICK
	message (which involves a zero length i2c write). To avoid
	checking the status register when we didn't strobe out any
	actual bytes to the bus, just do a read check. This is
	consistent with how I saw i2c device checking done in the
	USB trace of the Windows driver */
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_READ);

	if (!i2c_wait_done(i2c_adap))
	return -EIO;

	if (i2c_wait_read_ack(i2c_adap))
	return -EIO;

	return 0;
	}

	for (i = 0; i < msg->len;) {

	dprintk(4, " %02x\n", msg->buf[i]);

	au0828_write(dev, AU0828_I2C_WRITE_FIFO_205, msg->buf[i]);

	strobe++;
	i++;

	if ((strobe >= 4) \|\| (i >= msg->len)) {

	/* Strobe the byte into the bus */
	if (i < msg->len)
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_WRITE \|
	AU0828_I2C_TRIGGER_HOLD);
	else
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_WRITE);

	/* Reset strobe trigger */
	strobe = 0;

	if (!i2c_wait_write_done(i2c_adap))
	return -EIO;

	}

	}
	if (!i2c_wait_done(i2c_adap))
	return -EIO;

	dprintk(4, "\n");

	return msg->len;
	}

	/* FIXME: Implement join handling correctly */
	static int i2c_readbytes(struct i2c_adapter *i2c_adap,
	const struct i2c_msg *msg, int joined)
	{
	struct au0828_dev *dev = i2c_adap->algo_data;
	u8 i2c_speed = dev->board.i2c_clk_divider;
	int i;

	dprintk(4, "%s()\n", __func__);

	au0828_write(dev, AU0828_I2C_MULTIBYTE_MODE_2FF, 0x01);

	/*
	* Due to xc5000c clock stretch, we cannot use full speed at
	* readings from xc5000, as otherwise they'll fail.
	*/
	if (((dev->board.tuner_type == TUNER_XC5000) \|\|
	(dev->board.tuner_type == TUNER_XC5000C)) &&
	(dev->board.tuner_addr == msg->addr))
	i2c_speed = AU0828_I2C_CLK_20KHZ;

	/* Set the I2C clock */
	au0828_write(dev, AU0828_I2C_CLK_DIVIDER_202, i2c_speed);

	/* Hardware needs 8 bit addresses */
	au0828_write(dev, AU0828_I2C_DEST_ADDR_203, msg->addr << 1);

	dprintk(4, " RECV:\n");

	/* Deal with i2c_scan */
	if (msg->len == 0) {
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_READ);

	if (i2c_wait_read_ack(i2c_adap))
	return -EIO;
	return 0;
	}

	for (i = 0; i < msg->len;) {

	i++;

	if (i < msg->len)
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_READ \|
	AU0828_I2C_TRIGGER_HOLD);
	else
	au0828_write(dev, AU0828_I2C_TRIGGER_200,
	AU0828_I2C_TRIGGER_READ);

	if (!i2c_wait_read_done(i2c_adap))
	return -EIO;

	msg->buf[i-1] = au0828_read(dev, AU0828_I2C_READ_FIFO_209) &
	0xff;

	dprintk(4, " %02x\n", msg->buf[i-1]);
	}
	if (!i2c_wait_done(i2c_adap))
	return -EIO;

	dprintk(4, "\n");

	return msg->len;
	}

	static int i2c_xfer(struct i2c_adapter *i2c_adap,
	struct i2c_msg *msgs, int num)
	{
	int i, retval = 0;

	dprintk(4, "%s(num = %d)\n", __func__, num);

	for (i = 0; i < num; i++) {
	dprintk(4, "%s(num = %d) addr = 0x%02x len = 0x%x\n",
	__func__, num, msgs[i].addr, msgs[i].len);
	if (msgs[i].flags & I2C_M_RD) {
	/* read */
	retval = i2c_readbytes(i2c_adap, &msgs[i], 0);
	} else if (i + 1 < num && (msgs[i + 1].flags & I2C_M_RD) &&
	msgs[i].addr == msgs[i + 1].addr) {
	/* write then read from same address */
	retval = i2c_sendbytes(i2c_adap, &msgs[i],
	msgs[i + 1].len);
	if (retval < 0)
	goto err;
	i++;
	retval = i2c_readbytes(i2c_adap, &msgs[i], 1);
	} else {
	/* write */
	retval = i2c_sendbytes(i2c_adap, &msgs[i], 0);
	}
	if (retval < 0)
	goto err;
	}
	return num;

	err:
	return retval;
	}

	static u32 au0828_functionality(struct i2c_adapter *adap)
	{
	return I2C_FUNC_SMBUS_EMUL \| I2C_FUNC_I2C;
	}

	static struct i2c_algorithm au0828_i2c_algo_template = {
	.master_xfer = i2c_xfer,
	.functionality = au0828_functionality,
	};

	/* ----------------------------------------------------------------------- */

	static struct i2c_adapter au0828_i2c_adap_template = {
	.name = KBUILD_MODNAME,
	.owner = THIS_MODULE,
	.algo = &au0828_i2c_algo_template,
	};

	static struct i2c_client au0828_i2c_client_template = {
	.name = "au0828 internal",
	};

	static char *i2c_devs[128] = {
	[0x8e >> 1] = "au8522",
	[0xa0 >> 1] = "eeprom",
	[0xc2 >> 1] = "tuner/xc5000",
	};

	static void do_i2c_scan(char name, struct i2c_client c)
	{
	unsigned char buf;
	int i, rc;

	for (i = 0; i < 128; i++) {
	c->addr = i;
	rc = i2c_master_recv(c, &buf, 0);
	if (rc < 0)
	continue;
	pr_info("%s: i2c scan: found device @ 0x%x [%s]\n",
	name, i << 1, i2c_devs[i] ? i2c_devs[i] : "???");
	}
	}

	/* init + register i2c adapter */
	int au0828_i2c_register(struct au0828_dev *dev)
	{
	dprintk(1, "%s()\n", __func__);

	dev->i2c_adap = au0828_i2c_adap_template;
	dev->i2c_algo = au0828_i2c_algo_template;
	dev->i2c_client = au0828_i2c_client_template;

	dev->i2c_adap.dev.parent = &dev->usbdev->dev;

	strlcpy(dev->i2c_adap.name, KBUILD_MODNAME,
	sizeof(dev->i2c_adap.name));

	dev->i2c_adap.algo = &dev->i2c_algo;
	dev->i2c_adap.algo_data = dev;
	#ifdef CONFIG_VIDEO_AU0828_V4L2
	i2c_set_adapdata(&dev->i2c_adap, &dev->v4l2_dev);
	#else
	i2c_set_adapdata(&dev->i2c_adap, dev);
	#endif
	i2c_add_adapter(&dev->i2c_adap);

	dev->i2c_client.adapter = &dev->i2c_adap;

	if (0 == dev->i2c_rc) {
	pr_info("i2c bus registered\n");
	if (i2c_scan)
	do_i2c_scan(KBUILD_MODNAME, &dev->i2c_client);
	} else
	pr_info("i2c bus register FAILED\n");

	return dev->i2c_rc;
	}

	int au0828_i2c_unregister(struct au0828_dev *dev)
	{
	i2c_del_adapter(&dev->i2c_adap);
	return 0;
	}